1) Female speckled tortoises (Homopus signatus) in South Africa were observed over 29 days in early spring to understand how they cope with low environmental temperatures during their active feeding season. 2) The tortoises showed a unimodal daily activity pattern, but individual tortoises were only active for about 4.5 hours per day on average. They spent up to 73% of their active time basking, mostly under shrubs. 3) On colder days, the tortoises spent a higher percentage of their active time basking, indicating they use basking more to absorb heat when temperatures are low. Their feeding time was very low at only 24 minutes per day, likely

1. Amphibia-Reptilia 36 (2015): 207-214
Overcoming low environmental temperatures in the primary
feeding season: low-level activity and long basking
in the tortoise Homopus signatus
Victor J.T. Loehr1,∗
, Tariq Stark2
, Martijn Weterings2,3
, Henry Kuipers2
Abstract. Tortoises that live in regions where food plants grow in winter may have to cope with relatively low environmental
temperatures to obtain resources. The speckled tortoise, Homopus signatus, inhabits an arid winter rainfall range where it is
active in winter and spring at environmental temperatures well below its preferred body temperature. Although H. signatus
is a threatened species, we have no information how it deals with low environmental temperatures. Therefore, we made
continuous recordings of behaviour in nine female H. signatus on 29 days in the early spring. The group of females as a
whole showed activity (i.e., behaviours other than hiding) throughout the day in a unimodal pattern. However, individual
tortoises were active only for approximately 4.5 h per day and spent as much as 73% of their active time basking, mostly
under the protective cover of shrubs. In addition, a negative relationship between the percentage of active time spent in sun and
environmental temperature indicated that H. signatus used active behaviours other than basking to absorb heat, particularly on
cold days. Tortoises completed all active behaviours other than basking in 1.2 h per day, including a mere 24 min of feeding,
probably facilitated by the abundant availability of food plants in the early spring. We predict that a reduced availability of
food plants for H. signatus might lead to increased active time and possibly increased predation pressure, or to a decreased
proportion of active time spent basking and reduced body temperatures.
Keywords: behaviour, ectothermy, Namaqualand, Reptilia, South Africa, Succulent Karoo, thermoregulation, time budgets.
Introduction
Many tortoise species have herbivorous diets
(Ernst et al., 2000), restricting foraging oppor-
tunities to periods when food plants are avail-
able. In regions where most plant growth oc-
curs in winter, low environmental temperatures
may pose a challenge to the tortoises, given
their ectothermic metabolism. In response to
low winter temperatures, tortoises often reduce
(e.g., Gopherus morafkai, Psammobates geo-
metricus, Testudo graeca; Díaz-Paniagua et al.,
1995; Boycott and Bourquin, 2000; Sullivan et
al., 2014) or cease (e.g., G. agassizii, Testudo
hermanni, T. horsfieldii; Lagarde et al., 2002;
Nussear et al., 2007; Loy and Cianfrani, 2010)
activity. The semi-terrestrial turtle Glyptemys
1 - Homopus Research Foundation, Kwikstaartpad 1, 3403
ZH IJsselstein, The Netherlands
2 - VHL University of Applied Sciences, PO Box 1528,
8901 BV Leeuwarden, The Netherlands
3 - Wageningen University, Resource Ecology Group, PO
Box 47, 6700 AA Wageningen, The Netherlands
∗Corresponding author; e-mail: loehr@homopus.org
insculpta, living in a cool environment, over-
came low temperatures by selecting micro-
habitats that favoured preferred body tempera-
tures, in combination with a low thermal sensi-
tivity of the species’ metabolic rate (Dubois et
al., 2009). However, we have little information
how tortoises that forage in winter cope with
low environmental temperatures.
Namaqualand, in northwest South Africa, is
an arid (ca. 150-200 mm per annum, Cowling
et al., 1999; Hoffman et al., 2009) region in
which plants grow during winter (Cowling et
al., 1999). Winter plant growth in Namaqua-
land is the result of a combination of relatively
mild winter temperatures and predictable rain-
fall (Cowling et al., 1999), and requires the en-
demic (Boycott and Bourquin, 2000) speckled
tortoise, H. signatus, to forage in winter and
early spring. Although long-term average daily
maximum temperatures in winter and spring
were only 17.0 and 22.3°C, respectively, ac-
tive H. signatus maintained relatively high body
temperatures of 28.9-30.9°C (Loehr, 2012). The
© Koninklijke Brill NV, Leiden, 2015. DOI:10.1163/15685381-00002994

2. 208 V.J.T. Loehr et al.
small body size of H. signatus ( 110 mm;
Loehr, 2002b) may help the tortoises rapidly
reach high body temperatures (Wilson et al.,
1999), but extensive basking may also be re-
quired (Loehr, 2012). Basking may be particu-
larly important for adult females, because they
are more voluminous (Loehr et al., 2006) and
maintain higher body temperatures than males
during egg development in winter and spring
(Loehr, 2012). Homopus signatus is a threat-
ened species (Bombi et al., 2013; Turtle Taxon-
omy Working Group, 2014) and understanding
its behavioural pattern may help detect threats
to its survival and facilitate conservation.
Based on opportunistic population sampling,
Loehr (2002b) found that female H. signatus
spent 32% of their active time basking in the
early spring. However, data from undirected
sampling may be misleading because different
behaviours correspond to different detectabili-
ties (Buckland et al., 1993). We recorded ac-
tivity and behaviour in individual H. signatus
females using continuous observations early in
spring. In addition, we related tortoise activity
and behaviour to local weather parameters. Our
hypothesis was that female H. signatus spend a
large portion of their active time basking, par-
ticularly on cold days, to help them maintain
high body temperatures required for foraging
and metabolism.
Materials and methods
Study site and weather data
We used a study site near Springbok, South Africa (coordi-
nates deposited at the Scientific Services Unit, CapeNature,
Western Cape, South Africa), which consisted of a steep
south-easterly facing rocky hill with adjacent more levelled
areas (Loehr, 2002b). Springbok weather station provided
hourly ambient temperatures and the daily number of sun
hours.
Tortoise sampling and radio telemetry
From 22 till 29 August 2012, we located nine adult (e.g.,
straight carapace length 81.2 mm; Loehr et al., 2011)
female H. signatus in the study site. For every female, we
measured the straight carapace length (SCL) to the nearest
0.01 mm with digital sliding callipers, and body mass (BM)
to the nearest 1 g with a digital balance.
For ease of tracking and subsequent observations, tor-
toises were equipped with flat shaped radio transmitters
(AVM Instrument Company, Ltd., Colfax, USA). We used
quick-setting epoxy to position transmitters on the third
and fourth costal scutes to allow unobstructed movement
through vegetation and between rocks. Tortoises also car-
ried iButtons (DS1922L-F5, Dallas/Maxim, Dallas, USA)
on the fourth costal scute for a concurrent thermoregulation
study. The combined mass of the transmitter and iButton
was 8-10% of tortoise BM.
Tortoises were randomly selected without replacement
for observation in four rounds. In the evenings prior to days
when behaviour would be recorded, we tracked tortoises to
store their locations for next day observations. This allowed
us to approach the tortoises on observation days without
causing disturbance.
Behavioural recordings
Between 27 August and 17 October 2012, we spent 29
observation days following one or two tortoises per day
from 8:00 till 17:00. From our nine tortoises, five were
followed on four observation days, and four were followed
on three observation days. We ensured that all observation
days had suitable weather for tortoise activity (i.e., sunny or
partly clouded days without precipitation; Loehr, 2002b).
On observation days, behavioural recordings were made
by one or two observers who positioned themselves approx-
imately 1-6 m from a tortoise and used binoculars and direct
focal observations to record behaviour. Recordings were
continuous and distinguished 10 behaviours (table 1).
Statistical analysis
For every hour of the nine-hour observation days, we cal-
culated the average proportions of all behaviours for all fe-
males. To make proportions robust, basking open was com-
bined with basking cover, walking sun with walking shade,
feeding sun with feeding shade, and mating with nesting.
We compared the most prevalent behaviours among hours
using Linear Mixed Models (LMMs), accounting for indi-
vidual differences by fitting random intercepts for each tor-
toise and including hour of the day as fixed effect. In ad-
dition, we compared behaviours within each hour using a
Wilcoxon signed rank test or Friedman RM ANOVA on
ranks. Friedman RM ANOVAs with significant outcomes
were followed by Dunn-Bonferroni post hoc tests (Dunn,
1964).
We calculated the average number of hours per day
that females were active (i.e., active time, including all be-
haviours except hiding) and compared active time to inac-
tive time using a LMM. Subsequently, we calculated the
proportion of active time spent in sun and the proportion of
active time spent on each behaviour. A repeated t-test com-
pared proportions active time spent in sun and in shade, and
a LMM compared average (log-transformed) behavioural
proportions. We used tortoise∗day as random factor and be-
haviour as fixed factor, and adjusted significance levels for

3. Activity and behaviour in Homopus signatus 209
Table 1. Behaviours that were distinguished in nine female Homopus signatus.
Behaviour Description
Hiding Tortoise in retreat, in full shade. Extremities and head usually withdrawn
Scanning retreat Tortoise active in retreat, in full shade. Scanning visually and/or olfactory
Basking cover Tortoise stationary with extremities and/or head extended and often resting on the ground,
while partly in sun. Usually partly under a shrub or in a crevice
Basking open Tortoise stationary with extremities and/or head extended and often resting on the ground,
while in full sun
Walking sun Tortoise walking while (partly) in sun
Walking shade Tortoise walking while in full shade
Feeding sun Tortoise sniffing or biting a food item while (partly) in sun
Feeding shade Tortoise sniffing or biting a food item while in full shade
Mating Tortoise mounted or copulated by a male
Nesting Tortoise digging or closing a nest, or laying an egg
Table 2. Weather conditions on 29 observation days for nine
female Homopus signatus. Recordings of temperatures be-
tween 17:00 and 8:00 started on the days prior to observa-
tion days.
Parameter Mean SD Minimum Maximum
Sunshine (h)
Total 8:00-17:00 8.3 0.99 5.9 9.0
Temperature (°C)
Average 8:00-17:00 16.6 4.52 8.9 26.2
Average 17:00-8:00 11.6 3.98 5.6 19.2
Daily maximum 20.6 4.44 12.6 29.7
Daily minimum 7.9 2.95 3.9 15.6
pairwise comparisons with the Bonferroni procedure (Quinn
and Keough, 2002).
Linear Mixed Models also analysed effects of weather
parameters (average temperature between 8:00-17:00 and
between 17:00-8:00; table 2) on active time, (arcsine square-
root transformed) proportion of active time spent in sun, and
(arcsine square-root transformed) proportion of active time
spent basking. We fitted a random intercept for each tortoise
to account for individual differences.
All tests were performed in SPSS 18.0 (IBM Corpora-
tion, Armonk, NY, USA), except Wilcoxon, Friedman and
repeated t-tests that were completed in SigmaPlot 12.0 (Sy-
stat Software, Inc., San Jose, CA, USA). Test statistics were
considered to be significant below α = 0.05. Averages are
followed by ± 1SD and min-max values.
Results
Weather conditions and general tortoise
observations
Observation days were sunny with little varia-
tion in the number of sun hours among days
(table 2). During observation hours, tempera-
tures ranged from 3.9 to 29.7°C, equal to the
24-h temperature range on observation days (ta-
ble 2). The average daily maximum temperature
on observation days (table 2) was similar to the
long-term (1990-2011) average of 21.9 ± 2.0°C
(paired t-test, t28 = 1.56, P = 0.13), but the
average daily minimum temperature (table 2)
was 2.4°C lower than the long-term average of
10.3 ± 1.4°C (t28 = 4.30, P < 0.001).
Nine female H. signatus selected for be-
havioural observations had straight carapace
lengths of 92.7 ± 3.5 mm, 88.6-98.0 mm. Tor-
toises were active on almost all observation
days, but two days lacked tortoise activity. On
one additional day, an individual was inactive
except for 2 minutes of moving within its re-
treat. These three days were ignored in calcu-
lations of the average number of hours per day
that females were active. On seven days (24% of
all days with tortoise activity), tortoises were al-
ready active when observations started at 8:00.
On three days (10%), tortoises were still active
when the study site was vacated at 17:00.
Timing of activity and behaviour during the day
The group of females as a whole showed a
unimodal activity pattern (fig. 1). The pro-
portion hiding differed among hours (LMM,
F8,271.1 = 9.78, P < 0.001), with the highest
proportions occurring between 8:00-11:00 and
between 15:00-17:00 (fig. 1). The proportions
walking (F8,270.9 = 4.85, P < 0.001) and bask-
ing (F8,271.1 = 4.74, P < 0.001) also differed

4. 210 V.J.T. Loehr et al.
Figure 1. Average proportions of behaviours for nine female Homopus signatus for a total of 29 9-h observation days. Hours
that do not have any letters at the top of the figure in common indicate statistically different proportions among hours for
behaviours hiding, basking and walking.
among hours, with most walking occurring in
the afternoon and basking relatively equally dis-
tributed over the day (fig. 1). Individual varia-
tion was considerable, with hourly standard de-
viations ranging from 15-33% for hiding, 17-
32% for basking, and 0-10% for walking.
Comparisons of behavioural proportions
within hours showed significant differences for
each observation hour (8:00-9:00: Wilcoxon
signed rank test, Z = 2.40, two-sided P <
0.05; 9:00-17:00: Friedman RM ANOVA on
ranks, χ2
2 13.41, two-sided P < 0.001).
For all hours from 11:00 to 15:00, the propor-
tion basking exceeded proportions scanning and
reproductive behaviours. Similarly, hiding ex-
ceeded scanning at 10:00-11:00 and from 13:00
to 15:00, and reproductive behaviours at 11:00-
12:00 and from 13:00 to 17:00. The proportion
hiding was larger than the proportion feeding
from 10:00 to 12:00 and from 15:00 to 17:00,
and basking exceeded feeding from 10:00 to
12:00. Hiding and basking were similar for all
hours except 8:00-9:00, when hiding exceeded
basking. For 9:00-10:00, the proportion hiding
also exceeded the proportion walking.
Active time budgets
Individual tortoises were active for 0 to 8 h on
each observation day. The average daily active
and inactive times of the tortoises were similar
(LMM, F1,8.3 = 1.32, P = 0.28, fig. 2a).
Most active time was spent in sun rather than
in shade (repeated t-test, t8 = 26.45, two-tailed
P < 0.001, fig. 2b).
The behaviour basking in cover was most
prevalent during active time, exceeding propor-
tions of all other behaviours (LMM, F8,224.0 =
63.26, P < 0.001, fig. 2c). Behaviour walking
in sun also constituted a considerable portion of
the active time, exceeding all behaviours except
basking in cover. The proportion of time spent
basking in the open was relatively small.
Relationships with weather
The proportion of active time that tortoises
spent in sun negatively correlated to the av-
erage temperature between 8:00-17:00 (LMM,
F1,24.1 = 6.22, P < 0.05; table 3), but not to
average night temperature prior to observation
days (17:00-8:00; F1,26.3 = 1.14, P = 0.30; ta-

5. Activity and behaviour in Homopus signatus 211
Figure 2. Activity and behavioural time budgets for nine female Homopus signatus: average proportions of 9-h observation
days spent inactive or active (a), average proportions of active time spent in sun or in shade (b), and average active time
budget (c). Proportions that do not have any superscript letters in common are statistically different.
ble 3). Active time and the proportion of active
time spent basking were not related to any tem-
perature (LMMs, F1, 25.6 1.81, P > 0.19;
table 3).
Discussion
This study confirms our hypothesis that female
H. signatus spend a large portion of their ac-
tive time basking. Females used 73% of their
active time to bask, or even a slightly higher per-
centage because some females were already ac-
tive and basking when observation days started.
We expected to find a negative relationship be-
tween the proportion active time spent bask-
ing and environmental temperature, but instead
found a negative relationship between the pro-
portion active time spent in sun and tempera-
ture. It appeared that H. signatus continued to
absorb heat during active behaviours other than
basking, particularly on cold days.
The proportion of active time spent basking
by H. signatus was large compared to other che-
lonians, but there is little published informa-
tion. Female Chersina angulata spent less of

6. 212 V.J.T. Loehr et al.
Table 3. Estimates of fixed effects of Linear Mixed Models that analysed the effects of the average temperature between
8:00-17:00 (T8:00-17:00) and between 17:00-8:00 (T17:00-8:00) on the proportions time spent active, active time spent basking
and active time spent in sun, for Homopus signatus. The latter two proportions were arcsine square-root transformed.
Source Estimate SE df t P
Proportion of observation time spent active
Intercept 39.27 15.97 30.70 2.46 0.020
T8:00-17:00 0.86 0.95 24.90 0.91 0.37
T17:00-8:00 −0.94 1.12 26.70 −0.85 0.41
Proportion of active time spent basking
Intercept 1.46 0.19 26.87 7.83 <0.001
T8:00-17:00 −0.015 0.011 23.37 −1.34 0.19
T17:00-8:00 −0.011 0.013 25.56 −0.85 0.41
Proportion of active time spent in sun
Intercept 1.74 0.12 27.19 14.37 <0.001
T8:00-17:00 −0.018 0.007 24.10 −2.50 0.020
T17:00-8:00 −0.009 0.009 26.33 −1.066 0.30
their active time basking in early spring (61%;
Keswick et al., 2006). In addition, two tropical
chelonians, Vijayachelys sylvatica and Kinixys
spekii, did not bask at all (Hailey and Coul-
son, 1999; Smart et al., 2014). A particular in-
teresting comparison would be Testudo klein-
manni, because of its similarities with H. signa-
tus (e.g., small body size, similar climate, winter
and spring activity; Geffen and Mendelssohn,
1989), but data are lacking. In H. signatus, there
was a large discrepancy between the proportion
of active time spent basking in this study and the
percentage of 32% found in a previous study in
2000 (Loehr, 2002b). In contrast to the contin-
uous observations in this study, the 2000 study
used opportunistic sightings. It is likely that the
proportion of active time basking was underes-
timated in 2000 because stationary basking tor-
toises are more difficult to spot than moving tor-
toises (e.g., Moskovits and Kiester, 1987; Buck-
land et al., 1993). This highlights once again
that time budgets should be based on continu-
ous observations (Moskovits and Kiester, 1987;
Hailey and Coulson, 1999).
Although the group of females as a whole
was active throughout the day (i.e., fig. 1), in-
dividuals had a short daily active time that ac-
cumulated to only approximately 4.5 h. Active,
exposed behaviours may be associated with a
predation risk (Capula and Luiselli, 1993; Webb
and Whiting, 2005; Dubois et al., 2009), which
may not be outweighed by potential advantages
of prolonged high body temperatures. In H. sig-
natus, the common use of covered basking sites
and the taxon’s cryptic colouration (Loehr et al.,
2006) are likely to mitigate some predation risk
during active behaviours.
The short daily active time for H. signatus
in combination with the large proportion spent
basking provided little time (i.e., approximately
1.2 h per day) for other active behaviours.
Female Chersina angulata and Kinixys spekii
expressed other behaviours than basking for
longer periods of 2.1 and 8.2 h per day, respec-
tively (Hailey and Coulson, 1999; Keswick et
al., 2006). The habitat of H. signatus is char-
acterised by concentrated growth and flower-
ing of annual and perennial plants in winter
and spring (Cowling et al., 1999; Loehr, 2002a;
V.J.T. Loehr and T. Stark, pers. obs.). Conse-
quently, food plants were available to H. sig-
natus in abundance, which probably limited the
amount of time required for walking and feed-
ing. The relationship between time budgets of
H. signatus and the plant growth pattern in Na-
maqualand also implies a survival threat for H.
signatus. Changes in plant growth or plant phe-
nology that lead to a reduced food availabil-
ity, for example as a result of drought (Hoff-
man et al., 2009) or climate change (Midgley

7. Activity and behaviour in Homopus signatus 213
and Thuiller, 2011), may increase the amount of
time that H. signatus requires for foraging. Such
a shift would either increase active time and ex-
posure to predation, or decrease the proportion
of time available for basking and possibly body
temperature.
Acknowledgements. We would like to thank C. Laurijssens
for her valuable help in the field. Nama Khoi Local Mu-
nicipality and J. Akers are thanked for permission to con-
duct fieldwork on their land. Furthermore, we would like to
thank the Northern Cape Department of Environment and
Nature Conservation for granting research permits (FAUNA
152/2012 and FAUNA 153/2012), the University of the
Western Cape (R. Hofmeyr) for endorsing our project, the
Ethics Committee at the University of the Western Cape for
ethical clearance (number ScRiRC2008/39), and the South
African Weather Service for providing weather data.
References
Bombi, P., D’Amen, M., Luiselli, L. (2013): From continen-
tal priorities to local conservation: a multi-level analysis
for African tortoises. Plos One 8: 1-9.
Boycott, R., Bourquin, O. (2000): The Southern African
Tortoise Book: a Guide to Southern African Tortoises,
Terrapins and Turtles. Hilton, South Africa.
Buckland, S.T., Anderson, D.R., Burnham, K.P., Laake, J.L.
(1993): Distance Sampling: Estimating Abundance of
Biological Populations. Chapman and Hall, London.
Capula, M., Luiselli, L. (1993): Ecology of an alpine popu-
lation of the slow worm, Anguis fragilis Linnaeus, 1758:
thermal biology of reproduction (Squamata: Sauria: An-
guidae). Herpetozoa 6: 57-63.
Cowling, R.M., Esler, K.J., Rundel, P.W. (1999): Namaqua-
land, South Africa: an overview of a unique winter-
rainfall desert ecosystem. Plant Ecol. 142: 3-21.
Díaz-Paniagua, C., Keller, C., Andreu, A.C. (1995): Annual
variation of activity and daily distances moved in adult
spur-thighed tortoises, Testudo graeca, in southwestern
Spain. Herpetologica 51: 225-233.
Dubois, Y., Blouin-Demers, G., Shipley, B., Thomas, D.
(2009): Thermoregulation and habitat selection in wood
turtles Glyptemys insculpta: chasing the sun slowly.
J. Animal Ecol. 78: 1023-1032.
Dunn, O.J. (1964): Multiple comparisons using rank sums.
Technometrics 6: 241-252.
Ernst, C.H., Altenburg, R.G.M., Barbour, R.W. (2000): Tur-
tles of the World. World Biodiversity Database CD-
ROM Series. Windows Version 1.2. ETI, Springer Ver-
lag, UNESCO, Heidelberg.
Geffen, E., Mendelssohn, H. (1989): Activity patterns and
thermoregulatory behavior of the Egyptian tortoise Tes-
tudo kleinmanni in Israel. J. Herpetol. 23: 404-409.
Hailey, A., Coulson, I.M. (1999): Measurement of time
budgets from continuous observation of thread-trailed
tortoises (Kinixys spekii). Herpetol. J. 9: 15-20.
Hoffman, M.T., Carrick, P.J., Gillson, L., West, A.G. (2009):
Drought, climate change and vegetation response in the
Succulent Karoo, South Africa. South Afr. J. Science
105: 54-60.
Keswick, T., Henen, B.T., Hofmeyr, M.D. (2006): Sexual
disparity in activity patterns and time budgets of an-
gulate tortoises (Chersina angulata) on Dassen Island,
South Africa. Afr. Zool. 41: 224-233.
Lagarde, F., Bonnet, X., Nagy, K., Henen, B., Corbin, J.,
Naulleau, G. (2002): A short spring before a long jump:
the ecological challenge to the steppe tortoise (Testudo
horsfieldi). Can. J. Zool. 80: 493-502.
Loehr, V.J.T. (2002a): Diet of the Namaqualand speckled
padloper, Homopus signatus signatus, in early spring.
Afr. J. Herpetol. 51: 47-55.
Loehr, V.J.T. (2002b): Population characteristics and activ-
ity patterns of the Namaqualand speckled padloper (Ho-
mopus signatus signatus) in the early spring. J. Herpetol.
36: 378-389.
Loehr, V.J.T. (2012): High body temperatures in an arid,
winter-rainfall environment: thermal biology of the
smallest tortoise. J. Arid Environ. 82: 123-129.
Loehr, V.J.T., Henen, B.T., Hofmeyr, M.D. (2006): Shell
characteristics and sexual dimorphism in the Namaqua-
land speckled padloper, Homopus signatus signatus. Afr.
J. Herpetol. 55: 1-11.
Loehr, V.J.T., Henen, B.T., Hofmeyr, M.D. (2011): Repro-
ductive responses to rainfall in the Namaqualand speck-
led tortoise. Copeia 2011: 278-284.
Loy, A., Cianfrani, C. (2010): The ecology of Eurotestudo h.
hermanni in a mesic area of southern Italy: first evidence
of sperm storage. Ethol. Ecol. Evol. 22: 1-16.
Midgley, G.F., Thuiller, W. (2011): Potential responses
of terrestrial biodiversity in southern Africa to anthro-
pogenic climate change. Reg. Environ. Change 11: 127-
135.
Moskovits, D.K., Kiester, A.R. (1987): Activity levels and
ranging behaviour of the two Amazonian tortoises,
Geochelone carbonaria and Geochelone denticulata, in
north-western Brazil. Funct. Ecol. 1: 203-214.
Nussear, K.E., Esque, T.C., Haines, D.F., Tracy, C.R.
(2007): Desert tortoise hibernation: temperatures, tim-
ing, and environment. Copeia 2007: 378-386.
Quinn, G.P., Keough, M.J. (2002): Experimental Design
and Data Analysis for Biologists. Cambridge University
Press, Cambridge.
Smart, U., Deepak, V., Vasudevan, K. (2014): Preliminary
ethogram and in situ time-activity budget of the enig-
matic cane turtle (Vijayachelys silvatica) from the west-
ern Ghats, south India. Herpetol. Conserv. Biol. 9: 116-
122.
Sullivan, B.K., Averill-Murray, R., Sullivan, K.O., Sullivan,
J.R., Sullivan, E.A., Riedle, J.D. (2014): Winter activity
of the Sonoran desert tortoise (Gopherus morafkai) in
central Arizona. Chelonian Conserv. Biol. 13: 114-119.

8. 214 V.J.T. Loehr et al.
Turtle Taxonomy Working Group [van Dijk, P.P., Iverson,
J.B., Rhodin, A.G.J., Shaffer, H.B., Bour, R.] (2014):
Turtles of the world: annotated checklist of taxonomy,
synonymy, distribution with maps, and conservation sta-
tus, 7th edition. In: Conservation Biology of Freshwater
Turtles and Tortoises, p. 329-479. IUCN/SSC Tortoise
and Freshwater Turtle Specialist Group.
Webb, J.K., Whiting, M.J. (2005): Why don’t small snakes
bask? Juvenile broad-headed snakes trade thermal bene-
fits for safety. Oikos 110: 515-522.
Wilson, D.S., Morafka, D.J., Tracy, C.R., Nagy, K.A.
(1999): Winter activity of juvenile desert tortoises (Go-
pherus agassizii) in the Mojave Desert. J. Herpetol. 33:
496-501.
Submitted: April 5, 2015. Final revision received: June 1,
2015. Accepted: June 6, 2015.
Associate Editor: Luca Lusielli.